<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>判断一个数是否是素数</title>
</head>
<body>
    <script>
        
        function isZhiShu(n) {
            if (n <= 1) {
                return false;
            }
            for (var i = 2; i <= Math.sqrt(n); i++) {
                if (n % i === 0) {
                    return false;
                }
            }
            return true;
        }

        
        console.log("9 : " + isZhiShu(9)); 
        console.log("7 : " + isZhiShu(7)); 
    </script>
</body>
</html>